1. Field
The present disclosure relates generally to wireless communications systems, and in particular, to radio communications systems. Still more particularly, the present disclosure relates to a system and method for generating an on-demand modulation waveform for use in exchanging data between radio communications systems.
2. Background
A radio communications system may be configured to send and/or receive data using radio waves. Radio waves include the electromagnetic waves having frequencies between about 3 kilohertz and about 300 gigahertz. These frequencies are referred to as radio frequencies (RF).
A software defined radio (SDR) is a radio communications system in which one or more of the physical layer functions of the radio communications system are defined by software, firmware, or a combination of the two running on one or more hardware devices. Different types of hardware devices may be used to run the software and/or firmware. These different types of hardware devices may include, for example, without limitation, a field programmable gate array (FPGA), a digital signal processor (DSP), a general purpose processor (GPP), a programmable system on chip (SoC), and other types of programmable processor units.
A software defined radio may include a transmitter and a receiver. When data is to be transmitted from the software defined radio, the transmitter modulates a sampled modulation waveform, with the data. In other words, the selected data is encoded within the modulation waveform. The modulated modulation waveform is then used to modulate a carrier waveform such that the data is carried in the carrier waveform. The modulated carrier waveform may then be transmitted in the form of radio waves. Conversely, in response to the software defined radio receiving radio waves carrying data, the receiver uses a sampled modulation waveform to perform demodulation such that the data may be extracted.
With some currently available software defined radios, the modulation waveform used for modulation and demodulation is selected from a set of predefined modulation waveforms for a corresponding set of predefined bandwidths. This selection may be made based on the set of data channels selected for use in exchanging data between these software defined radios. As used herein, a “channel” is a selected range of continuous frequencies.
In particular, a modulation waveform is selected for each channel in the set of data channels. More specifically, the modulation waveform in the set of predefined modulation waveforms that best matches the conditions for a channel is selected for that channel. These conditions may include, for example, a maximum energy capacity, a bandwidth, a level of noise, and/or conditions for the channel.
However, the set of predefined modulation waveforms may not include modulation waveforms that match the conditions of the channels selected for communications as accurately as desired. When the modulation waveform selected for a particular channel does not match the conditions of the channel as accurately as desired, the level of performance of the software defined radio in exchanging data over this channel may be lower than desired. Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.